LM4041C: adjustable version overall accuracy

Charles Cammarata

Part Number: LM4041C
Other Parts Discussed in Thread: REF4132, LM4040

Greetings. We use the LM4041CEM3-ADJ component to create a ~3.3V reference. The feedback resistors are 10K and 16.9K, 1% tolerance, 100ppm. The shunt bias resistor is 140Ω from a regulated 5V supply. The reference feeds an A/D reference of the RM44 Hercules microcontroller, which draws ~ 3-6mA.

I am looking to calculate the total accuracy of the configuration from 20°C to 30°C and 10°C-60°C. The parameters in the data sheet, as given, make it a bit difficult.

Can you please assist with this analysis? Below is a screen shot of the circuit.

over 4 years ago

+1 Charles Cammarata over 4 years ago

Prodigy 130 points

Additionally, what would be the performance with 10K and 16.9K 0.1% 50ppm resistors?

0 Marcoo Z over 4 years ago in reply to Charles Cammarata

TI__Mastermind 19590 points

Hi Charles,

Top level question:

Is there a reason you decided to go with a LM4040 shunt reference vs a series reference such as REF4132 or REF3033?

The total accuracy between 20°C to 30°C and 10°C-60°C is generally not possible to calculate using max values, but it can be possible for typical.

This is because the industry standard for temperature drift is characterized using the box method which makes it difficult to guarantee subsets of the maximum characterization temperature range.

Feel free to use the excel attached to see the worst case worst case over temperature. To get a "estimate" of a subset, you can reduce the impact of the temperature drift.

Total Error Shunt Calculator V1.5 - LM4041-N ADJ E2E.xlsx

0 Charles Cammarata over 4 years ago in reply to Marcoo Z

Prodigy 130 points

Thank you!

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LM4041C: adjustable version overall accuracy